Catalytic process for unsaturated acids

ABSTRACT

Unsaturated acids in high yields along with smaller yields of aldehydes, as acrylic acid and acrolein or methacrylic acid and methacrolein, are prepared in excellent yields by the oxidation of an olefin as propylene or isobutylene in the presence of a catalyst containing cobalt molybdate, tellurium oxide and phosphorus oxide.

United States Patent [19] Eden [ *Jan. 1, 1974 CATALYTIC PROCESS FOR UNSATURATED ACIDS [75] Inventor: Jamal S. Eden, Akron, Ohio [73] Assignee: The B. F. Goodrich Company, New

York, NY.

[ Notice: The portion of the term of this patent subsequent to Sept. 10, 1985, has been disclaimed.

[22] Filed: June 27, 1969 2] Appl. No.: 837,356

[52] U.S. Cl. 260/533 N, 252/437 [51] Int. Cl. C07c 51/32, C07c 57/04 [58] Field of Search 260/533 N [56] References Cited UNITED STATES PATENTS 3,240,806 3/1966 Bethell et al 260/533 N Eden 260/533 N Koch et al. 260/533 N FOREIGN PATENTS OR APPLICATIONS 4,114,982 8/1966 Japan 260/530 N Primary Examiner-Lorraine A. Weinberger Assistant Examiner-Richard D. Kelly Att0rneyJ. Hughes Powell, Jr. and Ernest K. Bean [57] ABSTRACT 5 Claims, N0 Drawings CATALYTIC PROCESS FOR UNSATURATED ACIDS BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION I have now found that when olefins such as propylene or isobutylene are reacted with oxygen at an elevated temperature in the presence of a catalyst initially containing cobalt molybdate, tellurium oxide and phosphorus pentoxide, in a molar ratio 1-10 of each component, that excellent conversion and yield of propylene to acrylic acid with acrolein are obtained.

DETAILED DESCRIPTION The reactants for providing acidsand aldehydes are propylene or isobutylene, a molecular oxygencontaining gas which can be pure oxygen, oxygen diluted with an inert gas, oxygen enriched air or air per Stoichiometric ratios of oxygen to olefin for the purposes of this invention are 1.5:1. While lower ratios of oxygen can be used at a sacrifice of yield, it is preferred to use an excess of oxygen. Large excesses of oxygen while not undesirable, introduce process problems and an amount of oxygen from about two to about six mols of oxygen per mol of olefin is an adequate range.

The use of steam in the reaction while desirable is not absolutely essential. The amount of steam used may be varied from about zero to 10 or more mols per mol of olefin. Other diluent gases such as nitrogen, saturated hydrocarbons such as propane may be used if desired.

The reaction may be carried out in either fixed or fluidized catalyst bed.

The reaction temperature can range from above 300C. to about 550C. A preferred range is from about 350C. to about 475C.

The contact time may vary considerably in the range of greater than 0.1 seconds. Good results have been obtained within the range of about two to about 60 seconds. While advantage may be taken of the short contact time, longer times may be used if desired.

The reaction may be conducted at atmospheric pressure, in a partial vacuum, or under induced pressures up to 100 psi or higher.-Atmospheric pressure is preferred for fixed bed systems and higher pressures for fluid bed reactions.

The particle size of the catalyst for fixed bed operations may be from about 10 to 18 mesh. Larger and smaller size particles may be used in fixed beds if desired. For fluid bed operations, catalyst size normally will range from about 80 to 325 mesh (U.S. Sieve).

The active catalyst containing cobalt molybdate, tellurium oxide and phosphorus oxide may be prepared by a number of methods and may be supported or unsupv ported. The catalyst ingredients may be mixed in the form of solutions or slurries, or can be dry blended. Supported catalysts may be prepared by adding a dry support or aqueous slurry thereof to the catalyst ingredients. Among suitable supports are silica, silicacontaining alumina, titania, zirconia, materials such as diatomaceous earth, kieselguhr, silicon carbide, clay, aluminum oxides and the like.

An unsupported catalyst can be prepared by dissolving phosphomolybdic acid in water, and adding cobalt chloride in water, then telluric acid and phosphoric acid in water. The resulting mixture is heated with mix ing and the mixture is evaporated to dryness on a steam bath and calcined in a hot tube oven for 16 hours at 450C. The catalyst is ground to the desired mesh size. Alternative, powdered cobalt molybdate and ammonium tellurate' may be mixed with phosphoric acid, a dry support added thereto if desired, and dried.

A supported catalyst was prepared by mixing a water slurry containing 0.25 mol of CoMoO with 69.96 grams of finely divided low surface silica slurried in water. A slurry containing 26.15 grams (0.083 mol) of ammonium tellurate was added to this mixture and 28.87 grams (0.25 mol) of 85 percent phosphoric acid.

The mix was dried and calcined at 400C. for 16 hours, cooled and formed to a mesh size of 10-18 for fixed bed operations. The catalyst has a molar ratio of Co- M00 25 Te0 37.5 P 0 and 275 SiO The catalysts generally contain a molar ratio of 1-10 cobalt molybdate, l-10 tellurium oxide, 1-10 phosphorus oxide. A more preferred range based on one mol of cobalt molybdate is 0.1 to l of tellurium oxide and 0.1 to 2 of phosphorus pentoxide.

EXAMPLES Runs were made in a fixed bed reactor of a high silica (Vycor) glass tube 12 inches long and 30 mm outer diameter. The reactor had inlets for air, steam and propylene. External electrically operated heating coils were wound on the reactor. Outlet vapors were passed through a water cooled condenser and the uncondensed gases were passed through a gas chromatograph and analyzed continuously. The liquid condensate was weighed and analyzed for unsaturated acid and aldehyde in the gas chromatograph. ml. of the silica supported catalysts prepared as described above was placed in the reactor. Steam at a temperature of 200 to 250C. was first fed into the reactor, and thereafter propylene and.air were separately fed into the reactor from preheaters at a temperature of about 200 to 250C. Before the propylene was added, the reactor was preheated to about 285C. The molar ratio of reactants used based on one mol of propylene as steam and oxygen (air), the reaction temperature, contact time (calculated at room temperature and pressure), percent conversion of propylene and yield of acrolein and acrylic acid based on propylene converted in the several runs are set forth in the Table.

M01 per- M01 percent yield on Another catalyst was made in the same manner as that described for Example I except 178 grams of silica were used and the concentration of active catalyst on silica was 32 percent. The dried catalyst was calcined at 450C. for 16 hours and ground to about 325 mesh. The catalyst was placed in a fluid bed reactor and a series of runs made under the reaction conditions set forth in the Table ll below.

lybdate, l tellurium oxide and l-lO phosphorus oxide.

2. The method of claim 1 wherein the olefin is propylene, the molar ratio of oxygen is from between about two and five, the reaction temperature is about 375C. to about 475C. and there is present from up to about 10 mols of steam per mol of propylene.

3. The method of claim 2 where the catalyst molar TABLE II M01 per- Mol percent yield on Contact cent C HB cOnv.

time, Oxygen, Water. C Hi seconds mols mols conv. Acroleln A. acid ratio is l:0.ll:0.l2 of CoMoO :TeO :P O

4. The method of claim 1 wherein the olefin is isobutylene, the molar ratio of oxygen is between about 2 to 5, the reaction temperature is about 375 to about 475C. and there is present from up to about 10 mols of steam per mol of isobutylene.

5. The method of claim 4 wherein the catalyst molar ratio is l:0.ll:0.l2 of CoMoO :TeO :P O 

2. The method of claim 1 wherein the olefin is propylene, the molar ratio of oxygen is from between about two and five, the reaction temperature is about 375*C. to about 475*C. and there is present from up to about 10 mols of steam per mol of propylene.
 3. The method of claim 2 where the catalyst molar ratio is 1: 0.1-1:0.1-2 of CoMoO4:TeO2:P2O5.
 4. The method of claim 1 wherein the olefin is isobutylene, the molar ratio of oxygen is between about 2 to 5, the reaction temperature is about 375* to about 475*C. and there is present from up to about 10 mols of steam per mol of isobutylene.
 5. The method of claim 4 wherein the catalyst molar ratio is 1: 0.1-1:0.1-2 of CoMoO4:TeO2:P2O5. 